1. Field
One or more embodiments herein relate to a power assist unit and system.
2. Description of the Related Art
The efficient harnessing of power form solar, wind, and other of natural energy sources continues to be of interest. The generation of power from natural energy sources tends to be unstable and erratic because of their dependence on the weather or environmental conditions.
A variety of approaches have been proposed to increase the efficiency of power generation systems based on natural energy sources. One approach involves using a storage cell system. For example, a power transmission line may be used to send power generated by a wind power generator to a power system via a transformer. A capacitor-based storage cell system may be coupled to the transmission line via the transformer.
However, this approach is unable to reliably supply power because of varying weather conditions. Also, it is difficult to accurately predict the required capacity of the storage cells using this approach. Also, this approach performs charging and discharging operations at a high rate in order to account for changes in output power, e.g., because the charging and discharging time for cells of the storage cell system tends to be short, the number of times of charging and discharging is performed is increased. Also, the life cycles of the storage cells deteriorates over time because the load on the storage cells increases as a result of performing charging and discharging operations at a high rate.
Another approach involves using rechargeable batteries between a power source and load. A power compensation operation is then continuously performed on the rechargeable batteries. For example, the rechargeable batteries are divided into a first group used for a permanent power compensation operation and a second group used for a power compensation operation. The second group of rechargeable batteries may be used in place of rechargeable batteries in the first group when required, and are recovered and charged when the rechargeable batteries of the first group are recovered and charged.
However, the permanent power compensation operation is used only in rechargeable batteries of the first group. Also, because charging and discharging operations are performed at a high rate in order to account for changes in output power, the life cycles of the rechargeable batteries of the first group deteriorate because the batteries in the first group are continuously used. Also, the number of cells and the required storage capacity increases costs.
Another approach involves using a DC feed power system that includes storage devices connected to a DC bus. The storage devices perform charging and discharging operations based on power from the DC bus. However, it is difficult to perform charging and discharging operations at a high rate using this approach because the load is directly connected to the DC bus.